Brominated phenyl thiocyanate composition and wood treatment method



United States Patent 3,328,243 BROMHNATED PHENYL THIOCYANATE COMPQ-SITIGN AND WOOD TREATMENT METHOD Paul A. Wolf and Francis J. Bobalek,Midland, Mich, assignors to The Dow Chemical Company, Midland, Mich, acorporation of Delaware No Drawing. Filed Nov. 1, 1965, Ser. No. 505,95413 Claims. (Cl. 167-38.6)

The present invention is concerned with wood treatment and is directedto methods employing and compositions comprising a brominated phenylthiocyanate of the formula for wood treatment. In the above andsucceeding formula, R represents an alkyl radical being of from 1 to 4,both inclusive, carbon atoms. In the present specification and claims,the term brominated phenyl thiocyanate is used to refer only to one ormore materials of the foregoing definition. The products to be employedin accordance with the present invention are odorless and typically arecrystalline solid materials. Representative products include thefollowing: (3-bromo-4-hydroxy-5-methylphenyl) thiocyanate;(3-bromo-4-hydroxy-S-ethylphenyl) thiocyanate;(3-bromo-4-hydroxy-5-isopropylphenyl) thiocyanate; (3-bromo-4-hydroxy-4-n-buty1phenyl) thiocyanate; and (3-bromo-4-hydroxy-5-tert.-butylphenyl) thiocyanate.

The practice of the present invention affords excellent protection ofwoodfrom attack by microbial organisms, in particular, from attack bylower plant organisms, such as those organisms causing mildew. Moreover,the present brominated phenyl thiocyanates afford such protection overan extended period of time following treatment.

The method of the present invention comprises the step of treating woodwith an antimicrobial amount of brominated phenyl thiocyanate. It iscritical that the practice of the present invention results in thetreatment of wood with an antimicrobial amount of active agent. However,the precise amount of brominated phenyl thiocyanate to be employedvaries with factors such as the mode of treatment, the extent ofprotection desired, the kind of wood, and the like. In general, goodresults are obtained when employing brominated phenyl thiocyanate in anamount suflicient to produce a concentration in the wood of at leastabout 0.04 pound of brominated phenyl thiocyanate per cubic foot ofwood. The upper limit as to amount of brominated phenyl thiocyanateemployed is dictated by the capacity of the wood to absorb and retainthe active agent, and, in addition, the use of higher amounts, such asamounts in substantial excess of about 0.2 pound per cubic foot, is notalways economical, since it does not in all instances result in acorrespondingly higher level of protection.

In a preferred embodiment, the method of the present invention iscarried out by treating wood, typically otherwise untreated, with acomposition comprising brominated phenyl thiocyanate and solvent.

The identity of the solvent is not critical, it being necessary onlythat the rominated phenyl thiocyanate be sufficiently soluble thereinthat it serves to carry the active agent into the wood in anantimicrobial amount. Preferred solvents include the aromatichydrocarbon solvents, such as benzene, toluene, xylene, and naphthalene;various petroleum derivative products, such as kerosene, mineralspirits, and the like; and the materials generally designated "ice ascreosote, which materials are derived from coal tar or wood tar andwhich themselves exhibit wood-preserving properties: such materialsinclude coal tar creosote, coke oven tar creosote, water gas tarcreosote, petroleum oil creosote, wood creosote, mixtures thereof andthe like.

In another embodiment, the method of the present invention is carriedout by the treatment of wood with greases, oils, and the like. In thisembodiment, typical compositions are modified by the incorporationtherein of brominated phenyl thiocyanate in an amount sufiicient toprovide an antimicrobial concentration in the wood. Typical compositionsinclude those comprising an aromatic petroleum oil gel, a term whichdesignates a composition of the general physical consistency of cupgrease and consisting essentially of a normally fluid highly aromaticpetroleum product or oil in association with sufiicient of a gelatinagent to exhibit, under normal conditions of temperature, the propertiesof cup grease as regards viscosity and consistency. Typical compositionsalso include those liquids, frequently wood-preserving liquids such ascreosote, which are thickened with a thickening agent to yield agrease-like composition. Numerous other typical compositions are known.The present brominated phenyl thiocyanate is incorporated therein,ordinarily by simple addition.

The practice of the present invention can be carried out by simpleapplication to wood, as with brush, sprays, rollers, and the like. Whenthe practice of the present invention is carried out as a pretreatmentprior to subsequent painting, such application of a compositioncomprising active agent and solvent is usually adequate and preferred.In such instance, it is preferred that the solvent be as nearlycompletely volatile as possible, to avoid so-called bleeding uponsubsequent painting. The holdof wood thus treated for several days priorto painting facilitates solvent evaporation. However when the practiceof the present invention, employing this embodiment, is to serve as thesole protection for the wood, especially when the wood so treated is tobe exposed to especially harsh conditions, even better protection isdesirable and can be obtained when the application is carried out underspecial conditions of temperature and pressure. In general, betterpenetration is obtained when a solvent composition of brominated phenylthiocyanate is at elevated temperatures and when the Wood to be treatedis in a chamber at subatmospheric pressure. The best results areobtained with procedures combining both conditions, which procedures aregenerally spoken of as wood impregnation.

In general, when employing the impregnation procedures, the wood whichis to be treated is placed in a vessel from which the containedatmosphere is evacuated to achieve a subatmospheric pressure, such asfrom 5 to about 600 millimeters mercury. Thereafter a compositioncomprising brominated phenyl thiocyanate and solvent is introduced intothe vessel so as to effect the immersion of the wood therein. Preferablythis mixture is at an elevated temperature, for example, from 180 to 200F. The contents of the vessel can thereafter be placed successivelyunder superatmospheric pressure, such as from about 1.5 to aboutatmospheres, in some instances more, and under subatmospheric pressure,as previously set forth, for periods of time to facilitate theimpregnation of the solution into the wood. Techniques for facilitatingpenetration of the solution into the wood, such as incision, debarking,or other preparation of the wood, can be utilized.

In the compositions to be employed in accordance with the presentinvention, the amount of brominated phenyl thiocyanate present willdepend upon such factors as whether the composition is to be employed asa concentrate or as an ultimate treating composition, and in theinstance of the latter, other factors such as the degree of protectiondesired and the type of wood. In a composition comprising brominatedphenyl thiocyanate and solvent, the brominated phenyl thiocyanate can bepresent in an amount of from 0.5 to 99.5 percent, and the solvent can bepresent in an amount of from 0.5 to 99.5 percent, the percentages beingbased on the weight of ultimate composition. Similarly, in a grease-typecomposition, the brominated phenyl thiocyanate can be present in anamount of from 0.5 to 99.5 percent of total composition. When suchcomposition is employed as a concentrate, it can be diluted withadditional solvent or with other woodtreating materials to obtain theultimate treating composition.

When the practice of the present invention is to be employed forpretreatment of wood prior to painting, good results are generallyobtained when utilizing a composition comprising solvent and from about0.5 to percent of active agent by weight of ultimate composition; thiscomposition is then applied at the rate of about 3 or more gallons per1,000 square foot of wood surface.

A composition of active agent and solvent, or agrease or oil compositioncomprising the active agent, can also include other materials typicallyemployed in Wood treatment, such as drying materials; water repellants;binding materials, frequently of a synthetic polymeric nature; and thelike. The composition can also comprise other preservative materials.

The following examples illustrate the present invention and will enablethose skilled in the art to practice the invention.

Example 1 A wood treating composition is prepared by dispersing(3-bromo-4-hydroxy-5-methylphenyl) thiocyanate in mineral spirits with acommercial product identified simply as a water repellant. Thedispersion is carried out with such amounts that three modifiedcompositions are pre pared. The three compositions have the followingformulations:

All percentages are based on weight of the ultimate composition. Thesecompositions are adapted to be employed for wood treatment, especiallyprior to subsequent painting.

Example 2 The compositions of Example 1 are employed for wood treatmentprior to painting with a commercial alkyd paint formulation. In theseprocedures, the modified compositions of Example 1 are applied with abrush to separate panels of Southern yellow pine. The panels are thenpermitted to stand for approximately two weeks, to assure evaporation ofthe mineral spirits. Following this period, the panels are painted withthe commercial alkyd paint formulation, which is described as being ofthe following composition:

Pounds per 100 gallons Titanium dioxide 300 Talc 315 Long oil alkyl, 80%solid 350 Drier:

Lead naphthenate (24% metal) 6.9

Manganese naphthenate (6% metal) 1.4

Heavy mineral spirits 221.0

In particular, the alkyd paint formulation is specifically lacking anyantimicrobial agent. Other panels are treated with a compositionconsisting of 33.3 percent water repellant and 66.7 percent mineralspirits and thereafter painted with the commercial alkyd paintformulation to serve as a control. After painting, all panels arepermitted to dry and then placed outdoors in a subtropical climate ofgenerally high temperatures and humidity. The panels are placed in anortherly exposure in a nearly vertical position, so as to beadvantageous to fungal development, in particular, mildew development.The outdoor placement of the panels is made at the beginning of thesummer season, and observation of the panels is conducted recurringlythroughout the season.

The results of the observations are set forth in the following table:

TABLE I Months of mildewfree exposure Control panels 2 Panels treatedwith (3-bromo-4-hydroxy-5-methyl phenyl) thiocyanate:

0.5 percent 34 1.0 percent 57 2.0 percent 5-7 Example 3 The proceduresof Example 2 are duplicated except that in the three treatingcompositions applied prior to painting, the brominated phenylthiocyanate employed is (3- bromo-4-hydroxy-5-isopropylphenyl)thiocyanate. Results similar to those set forth in Example 2 areobtained.

Example 4 The evaluation procedures of Example 2 are duplicated exceptthat instead of the alkyd paint formulation, there is employed a basiclatex paint formulation. The formulation is as follows:

Pounds per gallons Water 255.10 Ethylene glycol 15.0 Dispersant 2.0Antifoamer 2.0 Viscosity controlling agent 4.0 Titanium dioxide 230.0Extenders 185.0 Latex (aqueous emulsion of polyacrylate) 453.0 Defoamer5.0

The results of the observations are set forth in the following table:

TABLE II Months of mildewfree exposure Control panels 2 Panels treatedwith (3-bromo-4-hydroxy-5-methylphenyl) thiocyanate:

0.5 percent 5-7 1.0 percent 5-7 2.0 percent 7 Example 5 The proceduresof Example 4 are duplicated except that in the three treatingcompositions applied prior to painting, the brominated phenylthiocyanate employed is (3-bromo-4-hydroxy-5-tert.-butylphenyl)thiocyanate. Results essentially the same as those set forth in Example4 are obtained:

The brominated phenyl thiocyanate compounds to be employed in accordancewith the present invention are prepared by reacting a phenol compound ofthe formula with sodium thiocyanate in methanol saturated with sodiumbromide. Thereafter, a solution of bromine in methanol saturated withsodium bromide is added portionwise over a period of time. Separationand, if desired, purification, are conducted in conventional manners.

We claim:

1. Method which comprises the step of treating wood with anantimicrobial amount of brominated phenyl thiocyanate of the formulawherein R represents an alkyl radical of from 1 to 4 carbon atoms.

2. Method of claim 1 wherein the brominated phenyl thiocyanate is(3-bromo-4-hydroxy-5-methylphenyl) thiocyannate.

3. Method of claim 1 wherein the brominated phenyl thiocyanate is(3-bromo-4-hydroxy-5 -isopropylphenyl) thiocyanate.

4. Method of claim 1 wherein the step of treating wood is carried outwith a composition comprising the brominated phenyl thiocyanate and asolvent.

5. Method of claim 4 wherein the solvent is mineral spirits.

6. Method of claim 4 wherein the solvent is creosote.

7. Method of claim 4 wherein the brominated phenyl thiocyanate is(3-bromo-4-hydroxy-5-methylphenyl) thiocyanate.

8. Method of claim 4 wherein the brominated phenyl thiocyanate is(3-bromo-4-hydroxy-5-isopropylpheny1) thiocyanate.

9. Composition which comprises brominated phenyl thiocyanate of theformula Br- R I SCN wherein R represents an alkyl radical of from 1 to 4carbon atoms and a solvent for said brominated phenyl thiocyanate.

10. Composition of claim 9 in which the brominated phenyl thiocyanate is(3-bromo-4-hydroxy-S-methylphenyl) thiocyanate.

11. Composition of claim 9 in which the brominated phenyl thiocyanate is(3-bromo-4-hydroxy-5-isopropylphenyl) thiocyanate.

12. Composition of claim 9 in which the solvent is mineral spirits.

13. Composition of claim 9 in which the solvent is creosote.

No reference cited.

ALBERT T. MEYERS, Primary Examiner.

DALE R. MAHANAND, Assistant Examiner.

1. METHOD WHICH COMPRISES THE STEP OF TREATING WOOD WITH ANANTIMICROBIAL AMOUNT OF BROMINATED PHENYL THIOCYANATE OF THE FORMULA